The scale is just all out of whack. It's 60Hz, but two graduations up from 50Hz and 13 vertical graticules between 20Hz and 200Hz?! There should be 10.As OP explained, he's in US, so that's 60Hz.
Which you can confirm by the 5th harmonic being exactly at 300Hz.
Looks like 60Hz to me. Just click the mouse in the plot a little distance away from the peak, then drag the mouse to the peak while holding down the shift key -- it'll add an arrow with the actual frequency and amplitude of the peak to the plot.Weird that it is 70Hz not 60 Hz though!
I do see the 70 Hz spike on the UB9000 measurement though. I will need to test again with a different DAC.
@pkaneThe scale is just all out of whack. It's 60Hz, but two graduations up from 50Hz and 13 vertical graticules between 20Hz and 200Hz?! There should be 10.
View attachment 232438
He always uses the 43Vrms míní jack input of E1DA. The system noise then dominates. At lower power, one needs to optimize input dividers and to use the XLR inputs of E1DA. E1DA needs external dividers and DIP switch setting at the bottom of the unit.Awesome work. Though honestly surprising to see a regression with noise of all things. I thought at least it would be basically the same, but having to hunt down "cleaner" PS and hope that leads to better results is kinda depressing.
The major grid lines are as marked. Ignore anything in between them as these are auto-placed by the charting library. I just modified Multitone to remove these since I have no control over their placement or spacing.
Yes, cabling. And DAC to be isolated. Tuning the system is crucial. Balanced input topology is a must.I think it might be that the mains noise you're capturing is due to your cabling.
Everything from amp to load to ADC is unbalanced, isn't it ?
Could you shorten those cables, maybe ?
Did you measure the loopback DAC+ADC with the same cabling (without the load resistor) ?
Do you think you can help me understand what it means to optimize input dividers exactly? I guess I understand why you would need to do it, what I'm lost on is how such a thing is done.He always uses the 43Vrms míní jack input of E1DA. The system noise then dominates. At lower power, one needs to optimize input dividers and to use the XLR inputs of E1DA. E1DA needs external dividers and DIP switch setting at the bottom of the unit.
He always uses the 43Vrms míní jack input of E1DA. The system noise then dominates. At lower power, one needs to optimize input dividers and to use the XLR inputs of E1DA. E1DA needs external dividers and DIP switch setting at the bottom of the unit.
It could be. I did some tests with a Korg DS-DAC-10R which is not instrument grade and it was already able to generate plenty of differences with different interconnects.I think it might be that the mains noise you're capturing is due to your cabling.
Everything from amp to load to ADC is unbalanced, isn't it ?
Could you shorten those cables, maybe ?
Did you measure the loopback DAC+ADC with the same cabling (without the load resistor) ?
It seems that Multitone Analyzer is calculating THD in a wrong way - when signal fundamental is -13 dBFS down and the highest harmonics are around -136 dBFS, then THD should be around -119 dB, not -132 dB (for PM-10)...Nice job!
Strange that Marantz say on their website that PM-11S2 and PM-10 have THD at 0.01%, so -80dB while you get -130dB with PM-10
They certainly forgot two "0"
On the other hand, they say between 111 and 113dB SNR, and you get 93dB
This is because THD was calculated in dBFS in this case. The setting to compute it in dBr is available, but wasn't selected.It seems that Multitone Analyzer is calculating THD in a wrong way - when signal fundamental is -13 dBFS down and the highest harmonics are around -136 dBFS, then THD should be around -119 dB, not -132 dB (for PM-10)...
THD definition:This is because THD was calculated in dBFS in this case. The setting to compute it in dBr is available, but wasn't selected.
THD definition:
"The THD is usually expressed in percent or in dB relative to the fundamental as distortion attenuation."Total harmonic distortion - Wikipedia
en.wikipedia.org
It does not matter if the scale is in dBFS or dBr - THD is "relative tu fundamental". Othervise, it is misleading, when fundamental is not exactly at 0 dBFS.
"...no confusion..."The units are displayed on the plot, so there should be no confusion. I see the need for both, which is why I provided the setting.